FIG. 13 illustrates an exemplary configuration of a switching device. When controlling a switching circuit such as an inverter, ordinarily a gate driver (driver circuit) that supplies a gate signal and a control circuit that controls the gate driver are provided, requiring mutually different driving voltages (3.3 V and 15 V, for example) for the gate driver and the control circuit. Consequently, it is typical to provide separately a power supply circuit for the gate driver and a power supply circuit for the control circuit (for example, see PTL 1 below).